The disclosure relates to methods for employing a single input to a microcontroller to perform multiple functions.
Advances in the manufacture of components used in electronic devices have made it possible to create smaller and more compact products having enhanced functionality. Very compact surface mount electronic components and advanced PC board manufacturing techniques have reduced the surface area necessary for electronic circuits. Mounting conductors to a PC board is one aspect of electronics manufacture that has resisted miniaturization, meaning that conductors necessary to power and communicate with an electronic circuit occupy an increasingly large part of the overall PC board surface area.
Programmable devices incorporating microcontrollers are standard in many areas of technology, with the microcontroller including memory, a processor, inputs for receiving signals and outputs for emitting signals. Firmware stored in memory is executed by the processor to perform desired functions. Programmable devices commonly require conductors for supplying power, communications, and signal pathways to and from a PC board supporting the microcontroller and related circuitry. Depending upon the end use for the programmable device, it may be necessary to protect the programmable device from the environment by means of a sealed housing. Various rubber or elastomeric seals may be employed to prevent materials from the environment from passing into the housing in the area where conductors pass through the housing. It is also known to use potting materials that are applied in liquid form and cure to form a plug around conductors passing through the housing. The conductors and sealing around the conductors can represent a significant cost of manufacture in terms of materials and labor. Further, although known seals have proven effective, the area around conductors passing through a housing are a known path for leakage from the environment that can cause failure of the programmable device.
Programmable devices can enhance the functionality of a wide variety of devices by incorporating optional features that can be selected by means of one or more electrical inputs. One common prior art method of providing an input to a programmable device is a DIP switch, where the position of switches provides inputs to the programmable device corresponding to the desired optional features. Such switches are limited in terms of the number of options available and are impractical in the context of a sealed housing.
One example of a programmable device is a warning light that generates warning light signals for use in conjunction with an emergency vehicle. The warning light may include a microcontroller with a library of light signal patterns that can be selected for display by the warning light. U.S. Pat. No. RE38,795 discloses a programmable warning light which includes a library of instructions for generating different warning light signals. The instructions are stored so that the beginning of each instruction is located at a specific memory address. The memory address associated with the beginning of each instruction is stored in a list or table. A program running on a microcontroller in the warning light monitors the state of an input and responds to a change in state of the input to step through the list or table of instructions. The microcontroller is programmed to save the memory address corresponding to the last instruction selected. The microcontroller uses the stored memory address to generate selected warning light signal until the monitored “pattern select” input is active. This allows a user to select one of the stored instructions. The disclosed warning light includes a conductor that is used only for the purpose of pattern selection, which is then not used for any other purpose.
U.S. Pat. No. 7,116,294 discloses LED driver circuits that coordinate the timing of warning light signals generated by otherwise separate and independent warning signal lights. A “SYNC” conductor connects the warning signal lights, and the driver circuits include a microcontroller programmed to monitor an input connected to the SYNC conductor. Simply stated, if the sync input is active (has changed state) when polled by the microcontroller, the microcontroller is programmed to follow a pattern of pulses applied to the SYNC conductor. If the state of the input has not changed when polled by the microcontroller, the microcontroller initiates a flashing sequence, and activates a SYNC output to place a pulse on the SYNC conductor that is detectable by other warning lights connected to the SYNC conductor. This synchronizing circuit allows any number of driver circuits connected to a common SYNC line to coordinate their flashing patterns without resort to a central controller. The contents of U.S. RE38,795 and U.S. Pat. No. 7,116,294, both assigned to the assignee of the present application, are hereby incorporated by reference in their entirety.
There is a need in the art to minimize the number of conductors entering the housing of a programmable device.
Accordingly, there is a need in the art to enhance the functionality of conductors that are present in a device